Primary hepatic lymphoma (PHL) exhibits a broad age distribution, with the youngest reported patient being 5 months old and the oldest 86 years old. While PHL predominantly affects older adults, with a mean age of onset at 52.4 years [2] , it can also occasionally manifest in pediatric populations [4] - [6] . The prevalence of PHL is slightly higher among female patients.

The clinical manifestations of primary hepatic lymphoma (PHL) are typically non-specific, with tumors generally remaining asymptomatic until they reach a significant size. Common symptoms include abdominal pain, abdominal distension, nausea, jaundice, weight loss, and vomiting. In some cases, patients may also present with fever, potentially associated with tumor hemorrhage or infection [7] [8] . Physical examination often reveals hepatomegaly and a palpable mass [9] . Notably, tumor marker levels such as alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and carbohydrate antigen 19-9 (CA19-9) usually remain within normal limits [10] .

The precise pathogenetic mechanisms underlying the condition remain unidentified. Certain cases of primary hepatic lymphoma (PHL) have been documented in close association with immunocompromised states, such as AIDS [11] [12] , the post-renal transplant period [13] [14] , radiochemotherapy for Hodgkin’s lymphoma [15] , and liver-related diseases, including chronic hepatitis C [16] and hepatitis B [17] . This association is hypothesized to result from the unrestrained effects of the Epstein-Barr virus (EBV) on smooth muscle proliferation [11] . Nevertheless, a significant proportion of patients diagnosed with primary hepatic lymphoma were immunocompetent, with approximately 77.4% exhibiting no discernible predisposing factors [2] [12] . Consequently, the etiology of primary hepatic lymphoma syndrome (PHLS) remains ambiguous and warrants further investigation.

The current patient, an elderly male, exhibited no abdominal discomfort and demonstrated normal levels of tumor markers. His medical history is unremarkable, with no previous liver diseases or immunodeficiency disorders. Laboratory tests were largely unremarkable, except for a mild elevation in uric acid levels.

Due to the non-specific nature of the clinical manifestations and laboratory findings, primary hepatic leiomyosarcoma (PHL) is frequently misdiagnosed [10] [18] . Accurate preoperative diagnosis of hepatic leiomyosarcoma, including identification of primary sites and potential metastasis, is crucial [12] [19] . Precise diagnostic protocols are essential for developing effective treatment strategies, particularly in the context of neoadjuvant therapy and complex surgical planning with extended margins, to address the aggressive nature of PHL. Imaging modalities are integral in this context, with magnetic resonance imaging (MRI) being essential for the diagnosis of liver lesions and positron emission tomography/computed tomography (PET/CT) playing a critical role in the detection of primary lesions and their metastases. In this study, we present a case of primary hepatic lymphoma (PHL) and conduct a thorough review of the existing literature to raise awareness about this rare malignant tumor. Our aim is to advance the radiological understanding of PHL, thereby optimizing patient management and improving clinical outcomes.

Case reports and case series pertaining to PHLS, published in English from January 1, 2000, to December 31, 2024, were sourced from PubMed and Google Scholar. After a rigorous screening process, 23 publications comprising 24 cases that described the MR imaging and PET/CT characteristics of PHLS were selected for inclusion in this study. The imaging findings from these cases, along with the current case, are summarized in Table 1 .

The non-specific imaging characteristics of primary hepatic leiomyosarcoma (PHL) pose significant challenges for accurate preoperative diagnosis. Traditional ultrasonography (US) generally identifies a hypoechoic mass, while computed tomography (CT) scans predominantly reveal well-defined hypo- or iso-dense masses, often containing heterogeneous regions suggestive of necrosis or hemorrhage [2] .

Magnetic Resonance Imaging (MRI) typically reveals heterogeneous hyperintensity on T2-weighted imaging (T2WI) and hypointensity on T1-weighted imaging (T1WI). This imaging modality may also display internal heterogeneity, indicative of intratumoral hemorrhage or necrosis [9] . Diffusion-weighted imaging was conducted in 10 out of 24 patients, showing varying degrees of restricted diffusion in all cases. Notably, one case exhibited restricted diffusion with wall involvement [7] . Most tumors were well demarcated, lacking a distinct capsule. A review of the literature indicates that a significant proportion of these cases demonstrate peripheral, heterogeneous enhancement during the arterial phase, with persistent or gradual enhancement noted in the portal venous or delayed phases [7] [9] [20] . In certain instances, there was an absence of enhancement during the arterial and venous phases, with only mild enhancement observed in the delayed phase [21] [22] . The MRI features in our case align with the predominant literature findings, particularly the progressive delayed enhancement, which may be a suggestive feature of PHL. A notable aspect of our case is the multifocal presentation, which contrasts with the more common solitary large mass. This multifocality could imply a different growth pattern or potentially a more aggressive tumor biology, though more cases are needed to establish any definitive clinicopathological correlation. Moreover, the lesions in this case uniformly exhibited similar MR imaging characteristics.

As a non-invasive diagnostic technique, PET/CT is utilized for the detection of primary tumors and metastases, as well as for distinguishing between benign and malignant lesions with high sensitivity. Additionally, it is employed for staging and guiding biopsy procedures [23] . Previous studies have reported FDG PET/CT findings in cases of leiomyosarcoma affecting the liver and other rare organs [24] [25] [26] . In the literature, the majority of primary hepatic leiomyosarcoma (PHL) cases exhibited high FDG uptake, with only one case demonstrating mild hypermetabolism comparable to the metabolic activity of liver parenchyma [27] . Another case showed low FDG uptake [28] . Cheon [27] suggested that the value of metabolic parameters such as SUVmax in the 18F-FDG PET-CT may be linked to the level of differentiation or necrosis and that it might also help diagnose and stage leiomyosarcoma. The substrates associated with varying FDG uptake remain ambiguous. In alignment with the majority of previous studies, the current case, characterized by multiple intrahepatic lesions, demonstrated elevated radiotracer uptake, with the SUVmax values at the periphery of most lesions exceeding those at the center. An increased distribution of radioactivity was observed in the soft tissues surrounding the left knee and ankle joints, with an SUVmax of 15.7, potentially indicative of bursitis or degenerative processes. Furthermore, no lesions were identified in other organs, allowing for the exclusion of hepatic metastases. Nonetheless, additional data collection is necessary for a more comprehensive evaluation.

Our findings suggest that primary hepatic leiomyosarcoma may present as multiple intrahepatic lesions. The diagnosis of primary hepatocellular sarcoma is confirmed through the histopathological analysis of surgical specimens or autopsy samples. Postoperative surveillance of prognosis and disease progression requires the utilization of MRI or PET-CT imaging modalities.